Common pathloss reference signal for spatial domain multiplexing sharing a common antenna panel

ABSTRACT

Wireless communications systems and methods related to reducing the signaling overhead for configuring a common reference signal used in performing coarse power control of multiple spatial domain multiplexing (SDM) uplink streams are provided. A base station may be in communication with a UE via multiple SDM streams directed from the same panel of the respective device. The base station may configure a common pathloss reference signal for the SDM streams of the same panel for the UE. This may include sending a list of possible pathloss reference signal configurations to the UE, and then identifying which configuration to use for the pathloss reference signal for the group of SDM streams. Once known, the UE may measure the reference signal for open loop power control. The BS may occasionally reconfigure the common reference signal for the grouped SDM streams.

CROSS REFERENCE TO RELATED APPLICATIONS & PRIORITY CLAIM

The present application is a Divisional Application of U.S. patentapplication Ser. No. 17/199,140, filed Mar. 11, 2021, which is herebyincorporated by reference in its entirety as if fully set forth belowand for all applicable purposes.

TECHNICAL FIELD

This application relates generally to wireless communication systems,and more particularly to configuring and/or using a common referencesignal for multiple spatial domain multiplexing (SDM) uplink streams.

INTRODUCTION

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). A wirelessmultiple-access communications system may include a number of basestations (BSs), each simultaneously supporting communications formultiple communication devices, which may be otherwise known as userequipment (UE).

As attention turns to using higher frequency bands (e.g., millimeterwave band and beyond) for mobile communication, devices may usebeamforming techniques to more efficiently transmit and receive signals.At higher frequency bands, for example, the beams may become narrower toallow for sufficient coverage due to higher propagation losses. The useof narrow beams, with corresponding higher directivity, allows multiplebeams to use spatial domain multiplexing (SDM) to transmit differentstreams of data concurrently at overlapping time and carrierfrequencies.

As the number of concurrent SDM streams increases, however, the beammanagement overhead in signaling and complexity increases. Concurrently,the latency increases due to the increased management overhead. Suchcomplexity, overhead, and latency is undesirable. Accordingly, moreefficient methods of establishing and maintaining multiple SDM streams,including for UEs communicating via different SDM streams to a commonpanel of antennas at a shared BS is desirable.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

For example, in an aspect of the disclosure, a method of wirelesscommunication includes receiving, by a first wireless communicationsdevice from a second wireless communications device, a messagecomprising configuration information indicating a reference signal for aplurality of spatial domain multiplexing (SDM) uplink streams. Themethod further includes measuring, by the first wireless communicationsdevice, the reference signal from the second wireless communicationsdevice. The method further includes applying, by the first wirelesscommunications device, a result from the measuring to each stream amongthe plurality of SDM uplink streams.

In an additional aspect of the disclosure, a method of wirelesscommunication includes determining, by a first wireless communicationsdevice, a common reference signal for a plurality of spatial domainmultiplexing (SDM) uplink streams. The method further includestransmitting, by the first wireless communications device to a secondwireless communications device, a message comprising configurationinformation indicating the reference signal. The method further includestransmitting, by the first wireless communications device to the secondwireless communications device, the reference signal.

In an additional aspect of the disclosure, a first wirelesscommunications device includes a transceiver configured to receive, froma second wireless communications device, a message comprisingconfiguration information indicating a reference signal for a pluralityof spatial domain multiplexing (SDM) uplink streams. The transceiver isfurther configured to measure the reference signal from the secondwireless communications device. The first wireless communications devicefurther includes a processor configured to apply a result from themeasuring to each stream among the plurality of SDM uplink streams.

In an additional aspect of the disclosure, a first wirelesscommunications device includes a processor configured to determine acommon reference signal for a plurality of spatial domain multiplexing(SDM) uplink streams. The first wireless communications device furtherincludes a transceiver configured to transmit, to a second wirelesscommunications device, a message comprising configuration informationindicating the reference signal. The transceiver is further configuredto transmit, to the second wireless communications device, the referencesignal.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary aspects of the presentinvention in conjunction with the accompanying figures. While featuresof the present invention may be discussed relative to certain aspectsand figures below, all aspects of the present invention can include oneor more of the advantageous features discussed herein. In other words,while one or more aspects may be discussed as having certainadvantageous features, one or more of such features may also be used inaccordance with the various aspects of the invention discussed herein.In similar fashion, while exemplary aspects may be discussed below asdevice, system, or method aspects it should be understood that suchexemplary aspects can be implemented in various devices, systems, andmethods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network according to someaspects of the present disclosure.

FIG. 2 illustrates an exemplary wireless communication scheme thatutilizes spatial domain multiplexed beams according to some aspects ofthe present disclosure.

FIG. 3 is a block diagram of an exemplary base station (BS) according tosome aspects of the present disclosure.

FIG. 4 is a block diagram of an exemplary user equipment (UE) accordingto some aspects of the present disclosure.

FIG. 5 illustrates an exemplary protocol diagram according to someaspects of the present disclosure.

FIG. 6 illustrates an exemplary flow diagram of a wireless communicationmethod according to some aspects of the present disclosure.

FIG. 7 illustrates an exemplary flow diagram of a wireless communicationmethod according to some aspects of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

This disclosure relates generally to wireless communications systems,also referred to as wireless communications networks. In variousaspects, the techniques and apparatus may be used for wirelesscommunication networks such as code division multiple access (CDMA)networks, time division multiple access (TDMA) networks, frequencydivision multiple access (FDMA) networks, orthogonal FDMA (OFDMA)networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, GlobalSystem for Mobile Communications (GSM) networks, 5^(th) Generation (5G)or new radio (NR) networks, as well as other communications networks. Asdescribed herein, the terms “networks” and “systems” may be usedinterchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA(E-UTRA), Institute of Electrical and Electronics Engineers (IEEE)802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA,and GSM are part of universal mobile telecommunication system (UMTS). Inparticular, long term evolution (LTE) is a release of UMTS that usesE-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documentsprovided from an organization named “3rd Generation Partnership Project”(3GPP), and cdma2000 is described in documents from an organizationnamed “3rd Generation Partnership Project 2” (3GPP2). These variousradio technologies and standards are known or are being developed. Forexample, the 3rd Generation Partnership Project (3GPP) is acollaboration between groups of telecommunications associations thataims to define a globally applicable third generation (3G) mobile phonespecification. 3GPP long term evolution (LTE) is a 3GPP project whichwas aimed at improving the UMTS mobile phone standard. The 3GPP maydefine specifications for the next generation of mobile networks, mobilesystems, and mobile devices. The present disclosure is concerned withthe evolution of wireless technologies from LTE, 4G, 5G, NR, and beyondwith shared access to wireless spectrum between networks using acollection of new and different radio access technologies or radio airinterfaces.

5G networks contemplate diverse deployments, diverse spectrum, anddiverse services and devices that may be implemented using an OFDM-basedunified, air interface. In order to achieve these goals, furtherenhancements to LTE and LTE-A are considered in addition to developmentof the new radio technology for 5G NR networks. The 5G NR will becapable of scaling to provide coverage (1) to a massive Internet ofthings (IoTs) with a ultra-high density (e.g., ˜1M nodes/km²), ultra-lowcomplexity (e.g., ˜10 s of bits/sec), ultra-low energy (e.g., ˜10+ yearsof battery life), and deep coverage with the capability to reachchallenging locations; (2) including mission-critical control withstrong security to safeguard sensitive personal, financial, orclassified information, ultra-high reliability (e.g., —99.9999%reliability), ultra-low latency (e.g., ˜1 ms), and users with wideranges of mobility or lack thereof; and (3) with enhanced mobilebroadband including extreme high capacity (e.g., ˜10 Tbps/km²), extremedata rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates),and deep awareness with advanced discovery and optimizations.

A 5G NR communication system may be implemented to use optimizedOFDM-based waveforms with scalable numerology and transmission timeinterval (TTI). Additional features may also include having a common,flexible framework to efficiently multiplex services and features with adynamic, low-latency time division duplex (TDD)/frequency divisionduplex (FDD) design; and with advanced wireless technologies, such asmassive multiple input, multiple output (MIMO), spatial domainmultiplexing (SDM), robust millimeter wave (mmWave) transmissions,advanced channel coding, and device-centric mobility. Scalability of thenumerology in 5G NR, with scaling of subcarrier spacing, may efficientlyaddress operating diverse services across diverse spectrum and diversedeployments. For example, in various outdoor and macro coveragedeployments of less than 3 GHz FDD/TDD implementations, subcarrierspacing may occur with 15 kHz, for example over 5, 10, 20 MHz, and thelike bandwidth (BW). For other various outdoor and small cell coveragedeployments of TDD greater than 3 GHz, subcarrier spacing may occur with30 kHz over 80/100 MHz BW. For other various wideband implementations,using a TDD over the unlicensed portion of the 5 GHz band, thesubcarrier spacing may occur with 60 kHz over a 160 MHz BW. Finally, forvarious deployments transmitting with mmWave components at a TDD of 28GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz BW.

The scalable numerology of the 5G NR facilitates scalable TTI fordiverse latency and quality of service (QoS) requirements. For example,shorter TTI may be used for low latency and high reliability, whilelonger TTI may be used for higher spectral efficiency. The efficientmultiplexing of long and short TTIs to allow transmissions to start onsymbol boundaries. 5G NR also contemplates a self-contained integratedsubframe design with uplink/downlink scheduling information, data, andacknowledgement in the same subframe. The self-contained integratedsubframe supports communications in unlicensed or contention-basedshared spectrum, adaptive uplink/downlink that may be flexiblyconfigured on a per-cell basis to dynamically switch between uplink anddownlink to meet the current traffic needs.

Various other aspects and features of the disclosure are furtherdescribed below. It should be apparent that the teachings herein may beembodied in a wide variety of forms and that any specific structure,function, or both being disclosed herein is merely representative andnot limiting. Based on the teachings herein one of an ordinary level ofskill in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. For example,a method may be implemented as part of a system, device, apparatus,and/or as instructions stored on a computer readable medium forexecution on a processor or computer. Furthermore, an aspect maycomprise at least one element of a claim.

Wireless communications at higher frequencies, such as mmWave frequencyranges, may experience a higher path-loss compared to lower frequencybands. To overcome the higher path-loss, BSs and UEs may use beamformingtechniques to form directional beams for communications. For instance, aBS and/or a UE may be equipped with one or more antenna panels orantenna arrays with antenna elements that can be configured to focustransmit signal energy and/or receive signal energy in a certain spatialdirection and/or within a certain spatial angular sector or width. Abeam used for such wireless communications may be referred to as anactive beam, a best beam, or a serving beam. The active beam mayinitially be selected from reference beams and then refined over time.

To overcome the higher path-loss, networks operating over the sub-THz toTHz frequency ranges may deploy BSs with a number oftransmission-reception points (TRPs) and/or in smaller areas to reducethe distance or range between a BS and a UE or between a TRP and a UE.In this regard, a BS may include multiple TRPs located at differentgeographical areas, where the TRPs may operate as radio-heads providingradio frontend (RF) functionalities for over-the-air communications. Insome scenarios, certain BS functionalities (e.g., protocol stack relatedfunctions) may also be distributed to the TRPs. The TRPs may be locatedcloser to certain UEs, and the BS may communicate with the UEs via theTRPs to reduce the communication range. Additionally, the BSs and/orTRPs may communicate with the UEs using narrower or more focused beamsto combat the higher path-loss. In such deployment scenarios, it ispossible to take further advantage of the vast number of TRPs and thenarrower beams by configuring multiple TRPs to communicate differentdata streams with the UEs in a spatial domain multiplexing (SDM)configuration to provide further increase in data rates. Different TRPsmay be located at different spatial directions from the UE. As such, theUE may use different beams (directed in different beam directions) tocommunicate with different TRPs (and/or to different beams of the sameTRP, using the same or multiple panels on the same TRP). The differentbeam directions along with the narrower beams can enable simultaneoustransmission of different data streams from different TRPs (or from thesame TRP) to the UE, and thereby increasing data throughputs.

As the number of SDM streams increases, so does the signaling overheadwith corresponding impacts on complexity, latency, and efficiency.Configuring which reference signal is used for power control for eachstream, for example, increases the overall signaling overhead betweenthe BS (via one or more TRPs, for example) and the UE. While thepathloss of each SDM beam is distinct from the others for communicationwith a given UE, there may be some commonalities among multiple beams.For instance, when a UE moves about, there will be some coarse changesthat are common between the moving UE and the different beams of thesame TRP. By taking advantage of commonalities, the configuration of oneor more pathloss reference signals for the SDM streams may be performedmore efficiently.

The present application describes mechanisms for performing improved SDMuplink stream management. A base station which is in communication witha UE via multiple SDM streams may transmit to the UE a message or seriesof messages to create a list of reference signals on the UE (e.g., ofpossible PUSCH-PathlossReferenceRS for UL SDM streams). In some aspects,the message may be transmitted as part of a radio resource control (RRC)message. The BS may also indicate to the UE via a message to form agroup comprising all or a subset of the SDM uplink streams. By joiningthe streams into a group, the BS may configure certain parameters whichaffect the entire group, rather than configuring the parameter(s)individually for each stream.

After configuring the UE with the list of available reference signals,the BS may send a message to the UE indicating which of the referencesignals on the list of reference signals is to be used as a referencesignal for power control of the SDM uplink streams that are in theindicated group. This may be referred to herein as a commonPathlossReferenceRS or simply common reference signal herein. In someexamples, the UE may have previously made a recommendation to the BS ofwhich reference to use, which the BS may determine to accept or not, andin other examples the BS may make its own determination. This messageindicating which reference signal to use from a list may be sent as partof a downlink control information (DCI) message, for example. Themessages from the BS may be communicated in a variety of ways, forexample on all, a subset of, or one of the SDM DL streams correspondingto the uplink SDM streams. Alternatively, the BS may send the message bya different stream or technology that is not associated with the streambeing configured. However sent, once the UE knows which reference signalit is configured to use from among the list of those possible, the UEmay measure the reference signal (i.e., the common PathlossReferenceRSindicated from the list) for open loop power control for the uplink SDMstreams. Closed loop power control (e.g., fine resolution) may beconfigured per UL SDM stream.

In some embodiments, the BS may reconfigure the common reference signalfor the grouped SDM streams. The BS may communicate to the UE toreconfigure the common reference signal for a number of reasons,including if the TRP that a UE is communicating with changes, or whenthe UE moves in relation to the BS/TRP for existing UL SDM streams, orwhen the BS determines to change what is used as the reference signal(e.g., switching between using a synchronization signal block (SSB) or aCSI-RS), or when there is a change in some channel characteristic (suchas one of the beams being received at a much lower power than the restof the beams in the group, as might occur when a change in theenvironment occurs that affects scattering of the stream(s)).

Aspects of the present disclosure provide several benefits. For example,in situations where there are multiple beams between a BS and a UE, suchas analog directional beams, with corresponding SDM streams, a BSconfiguring a reference signal for the multiple UL SDM streams togetheras a group (e.g., a group of streams using the same or close panels) mayuse less overhead than sending individual configuration messages foreach of the streams. Latency may also be improved by reducing theoverhead associated with configuring new SDM uplink streams, ormodifying existing SDM uplink streams. Therefore, a BS/UE pair utilizingaspects of the invention may achieve higher data rates than otherwise.In addition, in higher frequency bands (e.g., mmWave and above), whereconcurrent SDM streams are expected, such configuration overheadreduction and latency improvement, as realized according to aspects ofthe present disclosure, is significant.

FIG. 1 illustrates a wireless communication network 100 according tosome aspects of the present disclosure. The network 100 may be a 5Gnetwork. The network 100 includes a number of base stations (BSs) 105(individually labeled as 105 a, 105 b, 105 c, 105 d, 105 e, and 105 f)and other network entities. A BS 105 may be a station that communicateswith UEs 115 (individually labeled as 115 a, 115 b, 115 c, 115 d, 115 e,115 f, 115 g, 115 h, and 115 k) and may also be referred to as anevolved node B (eNB), a next generation eNB (gNB), an access point, andthe like. Each BS 105 may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to thisparticular geographic coverage area of a BS 105 and/or a BS subsystemserving the coverage area, depending on the context in which the term isused.

A BS 105 may provide communication coverage for a macro cell or a smallcell, such as a pico cell or a femto cell, and/or other types of cell. Amacro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEswith service subscriptions with the network provider. A small cell, suchas a pico cell, would generally cover a relatively smaller geographicarea and may allow unrestricted access by UEs with service subscriptionswith the network provider. A small cell, such as a femto cell, wouldalso generally cover a relatively small geographic area (e.g., a home)and, in addition to unrestricted access, may also provide restrictedaccess by UEs having an association with the femto cell (e.g., UEs in aclosed subscriber group (CSG), UEs for users in the home, and the like).A BS for a macro cell may be referred to as a macro BS. A BS for a smallcell may be referred to as a small cell BS, a pico BS, a femto BS or ahome BS. In the example shown in FIG. 1 , the BSs 105 d and 105 e may beregular macro BSs, while the BSs 105 a-105 c may be macro BSs enabledwith one of three dimension (3D), full dimension (FD), or massive MIMO.The BSs 105 a-105 c may take advantage of their higher dimension MIMOcapabilities to exploit 3D beamforming in both elevation and azimuthbeamforming to increase coverage and capacity. The BS 105 f may be asmall cell BS which may be a home node or portable access point. A BS105 may support one or multiple (e.g., two, three, four, and the like)cells.

One or more of the BSs 105 may have one or more transmission-receptionpoints (TRPs). This may be done to reduce the distance or range betweena BS 105 and a UE 115 or between a TRP and a UE 115. A given BS 105 may,for example, include multiple TRPs located at different geographicalareas, where the TRPs may operate as radio-heads providing radiofrontend (RF) functionalities for over-the-air communications. In somescenarios, certain BS 105 functionalities (e.g., protocol stack relatedfunctions) may also be distributed to the TRPs. Thus, in the example ofFIG. 1 , some of the BSs 105 may have one or more TRPs (notillustrated), or be themselves examples of TRPs for a remote BS.

The network 100 may support synchronous or asynchronous operation. Forsynchronous operation, the BSs may have similar frame timing, andtransmissions from different BSs may be approximately aligned in time.For asynchronous operation, the BSs may have different frame timing, andtransmissions from different BSs may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100, and eachUE 115 may be stationary or mobile. A UE 115 may also be referred to asa terminal, a mobile station, a subscriber unit, a station, or the like.A UE 115 may be a cellular phone, a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, atablet computer, a laptop computer, a cordless phone, a wireless localloop (WLL) station, or the like. In one aspect, a UE 115 may be a devicethat includes a Universal Integrated Circuit Card (UICC). In anotheraspect, a UE may be a device that does not include a UICC. In someaspects, the UEs 115 that do not include UICCs may also be referred toas IoT devices or internet of everything (IoE) devices. The UEs 115a-115 d are examples of mobile smart phone-type devices accessingnetwork 100. A UE 115 may also be a machine specifically configured forconnected communication, including machine type communication (MTC),enhanced MTC (eMTC), narrowband IoT (NB-IoT) and the like. The UEs 115e-115 h are examples of various machines configured for communicationthat access the network 100. The UEs 115 i-115 k are examples ofvehicles equipped with wireless communication devices configured forcommunication that access the network 100. A UE 115 may be able tocommunicate with any type of the BSs, whether macro BS, small cell, orthe like. In FIG. 1 , a lightning bolt (e.g., communication links)indicates wireless transmissions between a UE 115 and a serving BS 105,which is a BS designated to serve the UE 115 on the downlink (DL) and/oruplink (UL), desired transmission between BSs 105, backhaultransmissions between BSs, or sidelink transmissions between UEs 115.

In operation, the BSs 105 a-105 c may serve the UEs 115 a and 115 busing 3D beamforming and coordinated spatial techniques, such ascoordinated multipoint (CoMP) or multi-connectivity. The macro BS 105 dmay perform backhaul communications with the BSs 105 a-105 c, as well assmall cell, the BS 105 f. The macro BS 105 d may also transmitsmulticast services which are subscribed to and received by the UEs 115 cand 115 d. Such multicast services may include mobile television orstream video, or may include other services for providing communityinformation, such as weather emergencies or alerts, such as Amber alertsor gray alerts.

The BSs 105 may also communicate with a core network. The core networkmay provide user authentication, access authorization, tracking,Internet Protocol (IP) connectivity, and other access, routing, ormobility functions. At least some of the BSs 105 (e.g., which may be anexample of a gNB or an access node controller (ANC)) may interface withthe core network through backhaul links (e.g., NG-C, NG-U, etc.) and mayperform radio configuration and scheduling for communication with theUEs 115. In various examples, the BSs 105 may communicate, eitherdirectly or indirectly (e.g., through core network), with each otherover backhaul links (e.g., X1, X2, etc.), which may be wired or wirelesscommunication links.

The network 100 may also support mission critical communications withultra-reliable and redundant links for mission critical devices, such asthe UE 115 e, which may be a drone. Redundant communication links withthe UE 115 e may include links from the macro BSs 105 d and 105 e, aswell as links from the small cell BS 105 f. Other machine type devices,such as the UE 115 f (e.g., a thermometer), the UE 115 g (e.g., smartmeter), and UE 115 h (e.g., wearable device) may communicate through thenetwork 100 either directly with BSs, such as the small cell BS 105 f,and the macro BS 105 e, or in multi-step-size configurations bycommunicating with another user device which relays its information tothe network, such as the UE 115 f communicating temperature measurementinformation to the smart meter, the UE 115 g, which is then reported tothe network through the small cell BS 105 f. The network 100 may alsoprovide additional network efficiency through dynamic, low-latencyTDD/FDD communications, such as V2V, V2X, C-V2X communications between aUE 115 i, 115 j, or 115 k and other UEs 115, and/orvehicle-to-infrastructure (V2I) communications between a UE 115 i, 115j, or 115 k and a BS 105.

In some implementations, the network 100 utilizes OFDM-based waveformsfor communications. An OFDM-based system may partition the system BWinto multiple (K) orthogonal subcarriers, which are also commonlyreferred to as subcarriers, tones, bins, or the like. Each subcarriermay be modulated with data. In some instances, the subcarrier spacingbetween adjacent subcarriers may be fixed, and the total number ofsubcarriers (K) may be dependent on the system BW. The system BW mayalso be partitioned into subbands. In other instances, the subcarrierspacing and/or the duration of TTIs may be scalable.

In some aspects, the BSs 105 can assign or schedule transmissionresources (e.g., in the form of time-frequency resource blocks (RB)) fordownlink (DL) and uplink (UL) transmissions in the network 100. DLrefers to the transmission direction from a BS 105 to a UE 115, whereasUL refers to the transmission direction from a UE 115 to a BS 105. Thecommunication can be in the form of radio frames. A radio frame may bedivided into a plurality of subframes or slots, for example, about 10.Each slot may be further divided into mini-slots. In a FDD mode,simultaneous UL and DL transmissions may occur in different frequencybands. For example, each subframe includes a UL subframe in a ULfrequency band and a DL subframe in a DL frequency band. In a TDD mode,UL and DL transmissions occur at different time periods using the samefrequency band. For example, a subset of the subframes (e.g., DLsubframes) in a radio frame may be used for DL transmissions and anothersubset of the subframes (e.g., UL subframes) in the radio frame may beused for UL transmissions.

The DL subframes and the UL subframes can be further divided intoseveral regions. For example, each DL or UL subframe may havepre-defined regions for transmissions of reference signals, controlinformation, and data. Reference signals are predetermined signals thatfacilitate the communications between the BSs 105 and the UEs 115. Forexample, a reference signal can have a particular pilot pattern orstructure, where pilot tones may span across an operational BW orfrequency band, each positioned at a pre-defined time and a pre-definedfrequency. For example, a BS 105 may transmit cell specific referencesignals (CRSs) and/or channel state information—reference signals(CSI-RSs) to enable a UE 115 to estimate a DL channel. Similarly, a UE115 may transmit sounding reference signals (SRSs) to enable a BS 105 toestimate a UL channel Control information may include resourceassignments and protocol controls. Data may include protocol data and/oroperational data. In some aspects, the BSs 105 and the UEs 115 maycommunicate using self-contained subframes. A self-contained subframemay include a portion for DL communication and a portion for ULcommunication. A self-contained subframe can be DL-centric orUL-centric. A DL-centric subframe may include a longer duration for DLcommunication than for UL communication. A UL-centric subframe mayinclude a longer duration for UL communication than for ULcommunication.

In some aspects, the network 100 may utilize spatial domain multiplexed(SDM) signals for communication between devices. By utilizing SDM,communication between two devices in the network 100 may be performedacross multiple streams at the same time and frequencies by usingspatially differentiated beam paths. To achieve spatially differentiatedbeams, a UE 115 and/or BS 105 may use a panel of antennas in an array,lens antennas, and/or Butler matrices (to name a few examples). Usingthese techniques, relatively narrow beams may be formed, which may benarrowed in one or both of elevation and azimuth. A UE 115 maycommunicate with a BS 105 using two or more SDM uplink streams, each ofwhich is associated with a different beam path. For example, one of thebeams may travel along a line-of-sight propagation path, while aseparate SDM uplink stream takes a path which includes a reflection offof a reflective object. Each of the beams may carry a separate SDM datastream (on uplink and/or downlink), which may utilize the same frequencyand time resources as another. A BS 105 may send one or more controlmessages to a UE 115 in order to configure and manage the beams, forexample by indicating a reference signal associated with the beams. Thismay be, for example, a message to configure a common reference signal,such as a common PathlossReferenceRS as discussed further herein.

A given UE 115 may be associated with different groups, such that the UE115 may receive configuration information for more than one commonreference signal. For example, UE 115 a, as illustrated in FIG. 1 ,communicates with BS 105 a as well as BS 105 c. In some examples, eachBS 105 (105 a and 105 c in this simple example) may have multipleconcurrent SDM streams between UE 115 a and BS 105 a, and likewisebetween UE 115 a and BS 105 c. The concurrent SDM streams between UE 115a and BS 105 a may be between common panels at the respective devices,and likewise between UE 115 a and BS 105 c. Accordingly, the UE 115 amay receive a configuration message for a common reference signal forthe concurrent SDM streams to BS 105 a, and another configurationmessage for another common reference signal for the concurrent SDMstreams to BS 105 c. This, instead of a different configuration messagefor each individual SDM stream for pathloss reference signals, reducessignaling overhead and improves latency as further discussed below.

In some aspects, the network 100 may be an NR network deployed over alicensed spectrum. The BSs 105 can transmit synchronization signals(e.g., including a primary synchronization signal (PSS) and a secondarysynchronization signal (SSS)) in the network 100 to facilitatesynchronization. The BSs 105 can broadcast system information associatedwith the network 100 (e.g., including a master information block (MIB),remaining system information (RMSI), and other system information (OSI))to facilitate initial network access. In some instances, the BSs 105 maybroadcast the PSS, the SSS, and/or the MIB in the form ofsynchronization signal block (SSBs) over a physical broadcast channel(PBCH) and may broadcast the RMSI and/or the OSI over a physicaldownlink shared channel (PDSCH).

In some aspects, a UE 115 attempting to access the network 100 mayperform an initial cell search by detecting a PS S from a BS 105. ThePSS may enable synchronization of period timing and may indicate aphysical layer identity value. The UE 115 may then receive a SSS. TheSSS may enable radio frame synchronization, and may provide a cellidentity value, which may be combined with the physical layer identityvalue to identify the cell. The PSS and the SSS may be located in acentral portion of a carrier or any suitable frequencies within thecarrier.

After receiving the PSS and SSS, the UE 115 may receive a MIB. The MIBmay include system information for initial network access and schedulinginformation for RMSI and/or OSI. After decoding the MIB, the UE 115 mayreceive RMSI and/or OSI. The RMSI and/or OSI may include radio resourcecontrol (RRC) information related to random access channel (RACH)procedures, paging, control resource set (CORESET) for physical downlinkcontrol channel (PDCCH) monitoring, physical UL control channel (PUCCH),physical UL shared channel (PUSCH), power control, and SRS.

After obtaining the MIB, the RMSI and/or the OSI, the UE 115 can performa random access procedure to establish a connection with the BS 105. Insome examples, the random access procedure may be a four-step randomaccess procedure. For example, the UE 115 may transmit a random accesspreamble and the BS 105 may respond with a random access response. Therandom access response (RAR) may include a detected random accesspreamble identifier (ID) corresponding to the random access preamble,timing advance (TA) information, a UL grant, a temporary cell-radionetwork temporary identifier (C-RNTI), and/or a backoff indicator. Uponreceiving the random access response, the UE 115 may transmit aconnection request to the BS 105 and the BS 105 may respond with aconnection response. The connection response may indicate a contentionresolution. In some examples, the random access preamble, the RAR, theconnection request, and the connection response can be referred to asmessage 1 (MSG1), message 2 (MSG2), message 3 (MSG3), and message 4(MSG4), respectively. In some examples, the random access procedure maybe a two-step random access procedure, where the UE 115 may transmit arandom access preamble and a connection request in a single transmissionand the BS 105 may respond by transmitting a random access response anda connection response in a single transmission. The combined randomaccess preamble and connection request in the two-step random accessprocedure may be referred to as a message A (MSG A). The combined randomaccess response and connection response in the two-step random accessprocedure may be referred to as a message B (MSG B).

After establishing a connection, the UE 115 and the BS 105 can enter anormal operation stage, where operational data may be exchanged. Forexample, the BS 105 may schedule the UE 115 for UL and/or DLcommunications. The BS 105 may transmit UL and/or DL scheduling grantsto the UE 115 via a PDCCH. The BS 105 may transmit a DL communicationsignal to the UE 115 via a PDSCH according to a DL scheduling grant. TheUE 115 may transmit a UL communication signal to the BS 105 via a PUSCHand/or PUCCH according to a UL scheduling grant. The connection may bereferred to as an RRC connection. When the UE 115 is actively exchangingdata with the BS 105, the UE 115 is in an RRC connected state.

In an example, after establishing a connection with the BS 105, the UE115 may initiate an initial network attachment procedure with thenetwork 100. The BS 105 may coordinate with various network entities orfifth generation core (5GC) entities, such as an access and mobilityfunction (AMF), a serving gateway (SGW), and/or a packet data networkgateway (PGW), to complete the network attachment procedure. Forexample, the BS 105 may coordinate with the network entities in the 5GCto identify the UE, authenticate the UE, and/or authorize the UE forsending and/or receiving data in the network 100. In addition, the AMFmay assign the UE with a group of tracking areas (TAs). Once the networkattach procedure succeeds, a context is established for the UE 115 inthe AMF. After a successful attach to the network, the UE 115 can movearound the current TA. For tracking area update (TAU), the BS 105 mayrequest the UE 115 to update the network 100 with the UE 115's locationperiodically. Alternatively, the UE 115 may only report the UE 115'slocation to the network 100 when entering a new TA. The TAU allows thenetwork 100 to quickly locate the UE 115 and page the UE 115 uponreceiving an incoming data packet or call for the UE 115.

In some aspects, the BS 105 may communicate with a UE 115 using hybridautomatic repeat request (HARQ) techniques to improve communicationreliability, for example, to provide a ultra-reliable low-latencycommunication (URLLC) service. The BS 105 may schedule a UE 115 for aPDSCH communication by transmitting a DL grant in a PDCCH. The BS 105may transmit a DL data packet to the UE 115 according to the schedule inthe PDSCH. The DL data packet may be transmitted in the form of atransport block (TB). If the UE 115 decodes the DL data packetsuccessfully, the UE 115 may transmit a HARQ acknowledgement (ACK) tothe BS 105. Conversely, if the UE 115 fails to decode the DLtransmission successfully, the UE 115 may transmit a HARQnegative-acknowledgement (NACK) to the BS 105. Upon receiving a HARQNACK from the UE 115, the BS 105 may retransmit the DL data packet tothe UE 115. The retransmission may include the same coded version of DLdata as the initial transmission. Alternatively, the retransmission mayinclude a different coded version of the DL data than the initialtransmission. The UE 115 may apply soft-combining to combine the encodeddata received from the initial transmission and the retransmission fordecoding. The BS 105 and the UE 115 may also apply HARQ for ULcommunications using substantially similar mechanisms as the DL HARQ.

In some aspects, the network 100 may operate over a system BW or acomponent carrier (CC) BW. The network 100 may partition the system BWinto multiple bandwidth parts (BWPs) (e.g., portions). A BS 105 maydynamically assign a UE 115 to operate over a certain BWP (e.g., acertain portion of the system BW). The assigned BWP may be referred toas the active BWP. The UE 115 may monitor the active BWP for signalinginformation from the BS 105. The BS 105 may schedule the UE 115 for ULor DL communications in the active BWP. In some aspects, a BS 105 mayassign a pair of BWPs within the CC to a UE 115 for UL and DLcommunications. For example, the BWP pair may include one BWP for ULcommunications and one BWP for DL communications.

FIG. 2 illustrates a wireless communication network 200 that supportsdirectional beamforming according to some aspects of the presentdisclosure. The network 200 may correspond to a portion of the network100. FIG. 2 illustrates two TRPs 205 (shown as 205 a and 205 b) servingone UE 115 for simplicity of illustration and discussion, though it willbe recognized that aspects of the present disclosure may scale to anysuitable number of UEs 115 and/or TRPs 205. In some instances, the TRPs205 may also be referred to as radio heads or remote radio heads. TheTRPs 205 may implement at least some RF functionalities for over-the-aircommunications with the UE 115. In some instances, a BS (not shown) mayalso distribute some other functionalities such as baseband processingand/or protocol stack processing to the TRPs 205. In some instances, atleast one of the TRPs 205 can be co-located with a BS (and, generally,also be referred to as a BS). In some instances, both TRPs 205 can belocated remotely from the BS. In some exemplary embodiments according tothe present disclosure, the TRPs 205 and the UE 115 may communicate witheach other over a high-frequency band, such as a mmWave frequency rangeor a sub-THz range, and/or up to a THz range.

In FIG. 2 , the TRPs 205 and the UE 115 may use beamforming techniquesto generate transmit and/or reception beams to/from each other. In thisregard, the UE 115 may generate a set of transmission beams 210 (shownas 210 a, 210 b, 210 c, 210 d, and 210 e) in a set of beam directions.Each of the beams 210 a-210 e may have a certain beam width covering acertain spatial angular sector. Each beam may be used, for example, fora stream from one device to another. For example, the TRP 205 a maytransmit a corresponding downlink stream via each of beams 210 a, 210 b,and 210 c to UE 115, and likewise TRP 205 b a corresponding stream viaeach of beams 210 d and 210 e. The UE 115 may transmit, in turn,corresponding uplink streams via the beams 210 noted above with the TRPs205 a, 205 b respectively. In the discussion below regarding theconfiguration of pathloss reference signals for SDM uplink streams, eachuplink stream may utilize a different beam such as those illustrated inFIG. 2 . As such, the configuration of a pathloss reference signal for astream relates to a configuration of which reference signal to use foropen loop power control of an uplink stream for the associated beam. Forsimplicity, the discussion below typically references SDM uplinkstreams, without explicitly discussing the beams.

As illustrated, beam 210 b travels along a line-of-sight (LOS)propagation path between UE 115 and TRP 205 a. Similarly, beam 210 dtravels in a LOS propagation path between UE 115 and TRP 205 b. Theremainder of the beams as shown take paths which include a reflection.Beam 210 a is reflected off of an exemplary reflective object 220 a,beam 210 c is reflected off of an exemplary reflective object 220 b, andbeam 210 e is reflected off of an exemplary reflective object 220 c.These beam paths are exemplary to show the spatial and path diversitythat is possible between a UE and a TRP, and the specific paths thatbeams follow may vary in a number of ways, including differences in thepolarity of signals. Although FIG. 2 illustrates three beams between UE115 and TRP 205 a, and two beams between UE 115 and TRP 205 b, in otherexamples there may be more or fewer beams between each pair.

While taking different paths between UE 115 and TRPs 205, some beams maytake paths which are similar enough to each other in some respect suchthat certain configuration parameters may be shared between the beams.For example, beam paths 210 d and 210 e as illustrated will each becomelonger as UE 115 moves away from TRP 205 b, and shorter as UE 115 movestowards TRP 205 b. Continuing with that example, beam paths 210 a-210 cmay each become shorter as UE 115 moves towards TRP 205 a (i.e., alsoaway from TRP 205 b), and shorter as UE 115 moves away from TRP 205 a(i.e., towards TRP 205 b).

In some aspects, each of the TRP 205 a, TRP 205 b, and the UE 115 mayhave one or more antenna panels or one or more antenna arrays eachcomprising a plurality of antenna elements. The antenna elements can beindividually controlled to adjust the gain and/or phase such that anantenna array or an antenna panel can be configured to focus a transmitsignal in a certain beam direction and/or to focus in a certain beamdirection for receiving a signal. The TRP 205 a may communicate multiplebeams directed generally towards the UE 115 in similar a DL direction.Similarly, TRP 205 b may communicate multiple beams directed generallytowards the UE 115 in a similar DL direction. In either example, themultiple beams may be from a same panel of the given TRP.

FIG. 3 is a block diagram of an exemplary BS 300 according to someaspects of the present disclosure. In some instances, the BS 300 may bea BS 105 in the network 100 as discussed above in FIG. 1 . In some otherinstances, the BS 300 may be a TRP 205 a and/or TRP 205 b in the network200 as discussed above in FIG. 2 . As explained above, a TRP mayimplement at least RF functionalities, but may also implement somebaseband processing and/or protocol stack layer processing similar to aBS. As shown, the BS 300 may include a processor 302, a memory 304, areference signal configuration module 308, a transceiver 310 including amodem subsystem 312 and a RF unit 314, and one or more antennas 316.These elements may be coupled with one another. The term “coupled” mayrefer to directly or indirectly coupled or connected to one or moreintervening elements. For instance, these elements may be in direct orindirect communication with each other, for example via one or morebuses.

The processor 302 may have various features as a specific-typeprocessor. For example, these may include a CPU, a DSP, an ASIC, acontroller, a FPGA device, another hardware device, a firmware device,or any combination thereof configured to perform the operationsdescribed herein. The processor 302 may also be implemented as acombination of computing devices, e.g., a combination of a DSP and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The memory 304 may include a cache memory (e.g., a cache memory of theprocessor 302), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, asolid state memory device, one or more hard disk drives, memristor-basedarrays, other forms of volatile and non-volatile memory, or acombination of different types of memory. In some aspects, the memory304 may include a non-transitory computer-readable medium. The memory304 may store instructions 306. The instructions 306 may includeinstructions that, when executed by the processor 302, cause theprocessor 302 to perform operations described herein, for example,aspects of FIGS. 1-2 and 5-7 . Instructions 306 may also be referred toas program code. The program code may be for causing a wirelesscommunication device to perform these operations, for example by causingone or more processors (such as processor 302) to control or command thewireless communication device to do so. The terms “instructions” and“code” should be interpreted broadly to include any type ofcomputer-readable statement(s). For example, the terms “instructions”and “code” may refer to one or more programs, routines, sub-routines,functions, procedures, etc. “Instructions” and “code” may include asingle computer-readable statement or many computer-readable statements.

The reference signal configuration module 308 may be implemented viahardware, software, or combinations thereof. For example, the referencesignal configuration module 308 may be implemented as a processor,circuit, and/or instructions 306 stored in the memory 304 and executedby the processor 302. In some examples, the reference signalconfiguration module 308 can be integrated within the modem subsystem312. For example, the reference signal configuration module 308 can beimplemented by a combination of software components (e.g., executed by aDSP or a general processor) and hardware components (e.g., logic gatesand circuitry) within the modem subsystem 312.

The reference signal configuration module 308 may communicate withvarious components of the BS 300 to perform various aspects of thepresent disclosure, for example, aspects of FIGS. 1-2 and 5-7 . In someaspects, the reference signal configuration module 308 is configured todetermine a common reference signal to be sent to a UE for use with aplurality of spatial domain multiplexing (SDM) uplink streams. Thereference signal configuration module 308 is further configured totransmit, to a UE, a message comprising configuration informationindicating the reference signal, and transmit the reference signal tothe UE. In some aspects, reference signal may be a commonPathlossReferenceRS.

The message comprising configuration information may in some aspects becomprised of multiple messages. For example, a first message mayindicate a list of reference signals which may be selected from. Thelist of reference signals may also be assembled by adding or removingreference signals one at a time or more than one at a time from the listover time by sending multiple messages to the UE. The message comprisinga list of reference signals may sent as part of a radio resource control(RRC) message. Further, a message may be sent indicating which of thereference signals in the list should be used by the UE for the pluralityof SDM uplink streams (e.g., the plurality of SDM uplink streams thatare transmitted via beams between the same panel of the UE and receivedby the same panel of the BS). The message indicating which referencesignal to use from the list may be a part of a downlink controlinformation (DCI) message.

In some aspects, the reference signal configuration module 308 mayconfigure the UE 115 with a group of SDM uplink streams. The referencesignal configuration module 308 may send configuration information tocreate one group, or multiple groups, each with a different set of SDMuplink streams. The grouping of the SDM uplink streams may facilitateconfiguring reference signals which are common among the SDM uplinkstreams in each respective group. As a result, a given UE 115 may beconfigured with one or more groups of different SDM uplink streams. Withsuch grouping, the reference signal configuration module 308 maytransmit a further configuration message, such as via DCI messaging,instructing the UE 115 which PathlossReferenceRS to use for the SDMuplink streams in a corresponding group. This may be repeated for eachof any other grouped SDM uplink streams at the given UE 115.

In some aspects, the reference signal configuration module 308 isconfigured to occasionally change which reference signal is used by eachconfigured group. This change may be by a message for the group, asopposed to individual messages for each of the SDM uplink streams withinthe group. There are a number of scenarios in which a reference signalconfiguration module 308 may determine that a change in a CommonPathlossReferenceRS is warranted and/or desirable. For example, a changemay be warranted when the BS 300 has configured a new preferablereference signal (e.g. CSI-RS instead of SSB). Another scenario may bewhen the UE is changing which cell it is connected to. Another reasonthe beam module 308 may change the indicated reference signal relates towhen there is some change in one or more signal paths such that thereference signal no longer provides a good enough estimate of thechanged signal paths. For example if an object which was reflecting thebeam for one of the SDM uplink streams, such as reflective object 220 a,moved, this might cause enough change in the signal path (if it is stilla viable path) that a different reference signal may be better used forcoarse power correction.

As shown, the transceiver 310 may include the modem subsystem 312 andthe RF unit 314. The transceiver 310 can be configured to communicatebi-directionally with other devices, such as the UEs 115 and/or anothercore network element. The modem subsystem 312 may be configured tomodulate and/or encode data according to a MCS, e.g., a LDPC codingscheme, a turbo coding scheme, a convolutional coding scheme, a digitalbeamforming scheme, etc. The RF unit 314 may be configured to process(e.g., perform analog to digital conversion or digital to analogconversion, etc.) modulated/encoded data (e.g., RRC configuration,CSI-RS resource configuration, CSI-RS report configuration, CSI-RSs, SSBbeams) from the modem subsystem 312 (on outbound transmissions) or oftransmissions originating from another source such as a UE 115. The RFunit 314 may be further configured to perform analog beamforming inconjunction with the digital beamforming. Although shown as integratedtogether in transceiver 310, the modem subsystem 312 and/or the RF unit314 may be separate devices that are coupled together at the BS 105 toenable the BS 105 to communicate with other devices.

The RF unit 314 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information), to the antennas 316 fortransmission to one or more other devices. The antennas 316 may furtherreceive data messages transmitted from other devices and provide thereceived data messages for processing and/or demodulation at thetransceiver 310. The transceiver 310 may provide the demodulated anddecoded data (e.g., messages indicating reference signals) to thereference signal configuration module 308 for processing. The antennas316 may include multiple antennas of similar or different designs inorder to sustain multiple transmission links. In some aspects, theantennas 316 may in the form of one or more antenna panels or one ormore antenna arrays each including a plurality of antenna element thatcan be selectively configured with different gains and/or phases togenerate a beam for transmission and/or reception.

FIG. 4 is a block diagram of an exemplary UE 400 according to someaspects of the present disclosure. In some instances, the UE 400 may bea UE 115 as discussed above with respect to FIGS. 1 and 2 . As shown,the UE 400 may include a processor 402, a memory 404, a reference signalconfiguration module 408, a transceiver 410 including a modem subsystem412 and a radio frequency (RF) unit 414, and one or more antennas 416.These elements may be coupled with one another. The term “coupled” mayrefer to directly or indirectly coupled or connected to one or moreintervening elements. For instance, these elements may be in direct orindirect communication with each other, for example via one or morebuses.

The processor 402 may include a central processing unit (CPU), a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a controller, a field programmable gate array (FPGA) device,another hardware device, a firmware device, or any combination thereofconfigured to perform the operations described herein. The processor 402may also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The memory 404 may include a cache memory (e.g., a cache memory of theprocessor 402), random access memory (RAM), magnetoresistive RAM (MRAM),read-only memory (ROM), programmable read-only memory (PROM), erasableprogrammable read only memory (EPROM), electrically erasableprogrammable read only memory (EEPROM), flash memory, solid state memorydevice, hard disk drives, other forms of volatile and non-volatilememory, or a combination of different types of memory. In an aspect, thememory 404 includes a non-transitory computer-readable medium. Thememory 404 may store, or have recorded thereon, instructions 406. Theinstructions 406 may include instructions that, when executed by theprocessor 402, cause the processor 402 to perform the operationsdescribed herein with reference to the UEs 115 in connection withaspects of the present disclosure, for example, aspects of FIGS. 1-2 and5-7 . Instructions 406 may also be referred to as program code, whichmay be interpreted broadly to include any type of computer-readablestatement(s) as discussed above with respect to FIG. 3 .

The reference signal configuration module 408 may be implemented viahardware, software, or combinations thereof. For example, the referencesignal configuration module 408 may be implemented as a processor,circuit, and/or instructions 406 stored in the memory 404 and executedby the processor 402. In some examples, the reference signalconfiguration module 408 can be integrated within the modem subsystem412. For example, the reference signal configuration module 408 can beimplemented by a combination of software components (e.g., executed by aDSP or a general processor) and hardware components (e.g., logic gatesand circuitry) within the modem subsystem 412.

The reference signal configuration module 408 may communicate withvarious components of the UE 400 to perform aspects of the presentdisclosure, for example, aspects of FIGS. 1-2 and 5-7 . In some aspects,the reference signal configuration module 408 is configured to receive,from a BS, a message comprising configuration information for areference signal (e.g., a common PathlossReferenceRS) for a plurality ofspatial domain multiplexing (SDM) uplink streams. The reference signalconfiguration module 408 is further configured to cooperate with otheraspects of the UE 400 to measure the reference signal(s) accordinglyconfigured via the configuration information previously received fromthe BS 300. The UE 400 may also, such as via the reference signalconfiguration module 408, apply the result from the measurement to eachstream among the plurality of SDM uplink streams for open loop powercontrol on the uplink.

In some aspects the configuration may be performed by a number ofmessages, as discussed above with respect to FIG. 3 . For example, thereference signal configuration module 408 may receive a first radioresource control (RRC) message containing a list of reference signals.The list of reference signals may also be formed over multiple RRCmessages by adding or removing signals to and from the listindividually. A separate message may be used to indicate which of thereference signals on the list is to be used by the plurality of SDMuplink streams. As a result, the reference signal to use may beconfigured for several SDM uplink streams via a common configurationmessage, thereby reducing signaling overhead.

The indicated reference signals (e.g., as identified by the separatemessage, such as a DCI message that identifies a reference signal fromthe RRC-configured list) may be used by the UE 400 to perform coarsepower adjustment of the SDM uplink streams. For example, if the UE 400is in a configuration such as UE 115 in FIG. 2 , and the UE 400 movesaway from TRP 205 a, then the reference signal measurement will changeaccordingly, which the UE 400 may use to adjust the signal power for thebeams associated with the SDM uplink streams.

In some aspects, the reference signal configuration module 408 may beconfigured to receive a message from the BS 105 creating one or moregroups of SDM uplink streams. The grouping of the SDM uplink streamsfacilitates configuring reference signals which are common among the SDMuplink streams in each respective group. The grouping of the SDM uplinkstreams additionally allows for the reference signal configurationmodule 408 to receive messages regarding the entire group, such aschanging which of the reference signals on the list of reference signalsis selected for power adjustment. This may occur when the BS 105determines that a change would be beneficial as described above withreference to BS 300 in FIG. 3 .

As shown, the transceiver 410 may include the modem subsystem 412 andthe RF unit 414. The transceiver 410 can be configured to communicatebi-directionally with other devices, such as the BSs 105. The modemsubsystem 412 may be configured to modulate and/or encode the data fromthe memory 404 and/or the beam module 408 according to a modulation andcoding scheme (MCS), e.g., a low-density parity check (LDPC) codingscheme, a turbo coding scheme, a convolutional coding scheme, a digitalbeamforming scheme, etc. The RF unit 414 may be configured to process(e.g., perform analog to digital conversion or digital to analogconversion, etc.) modulated/encoded data (e.g., UE capability report,beam reports) from the modem subsystem 412 (on outbound transmissions)or of transmissions originating from another source such as a UE 115 ora BS 105. The RF unit 414 may be further configured to perform analogbeamforming in conjunction with the digital beamforming. Although shownas integrated together in transceiver 410, the modem subsystem 412 andthe RF unit 414 may be separate devices that are coupled together at theUE 115 to enable the UE 115 to communicate with other devices.

The RF unit 414 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may include one ormore data packets and other information), to the antennas 416 fortransmission to one or more other devices. The antennas 416 may furtherreceive data messages transmitted from other devices. The antennas 416may provide the received data messages for processing and/ordemodulation at the transceiver 410. The transceiver 410 may provide thedemodulated and decoded data (e.g., Common PathlossReferenceRSconfiguration, and/or a pathlossReferenceRS upon receipt) to thereference signal configuration module 408 for processing. The antennas416 may include multiple antennas of similar or different designs inorder to sustain multiple transmission links. The RF unit 414 mayconfigure the antennas 416. In some aspects, the antennas 416 may in theform of one or more antenna panels or one or more antenna arrays eachincluding a plurality of antenna element that can be selectivelyconfigured with different gains and/or phases to generate a beam fortransmission and/or reception.

FIG. 5 is a sequence diagram illustrating a communication protocoldiagram 500 for configuring pathlossReferenceRS for SDM streamsaccording to some aspects of the present disclosure. Aspects of theprotocol diagram 500 may be performed by wireless networks, such as thenetworks 100 and/or 200 communicating over a high-frequency band, suchas a mmWave band or a sub-THz to THz band. In this regard, a BS 105 andUE 115 may perform functions of the communication protocol diagram 500.In some instances, the BS 105 may utilize TRPs (e.g., the TRPs 205) tocommunicate with the UE 115. For simplicity of illustration anddiscussion, FIG. 5 is described from the perspective of a single TRPco-located with the BS 105 or at a remote location from the BS 105.However, similar communications may also occur for other TRPs that arein communication with the BS 105, at the same or different times. Insome aspects, the UE 115 may be in a connected mode (e.g., an RRCconnected state). In some aspects, the BS 105 may utilize one or morecomponents, such as the processor 302, the memory 304, the referencesignal configuration module 308, the transceiver 310, the modem 312, andthe one or more antennas 316 shown in FIG. 3 , and the UE 115 mayutilize one or more components, such as the processor 402, the memory404, the reference signal configuration module 408, the transceiver 410,the modem 412, and the one or more antennas 416 shown in FIG. 4 . Asillustrated, the method 500 includes a number of enumerated actions, butaspects of the FIG. 5 may include additional actions before, after, andin between the enumerated actions. In some aspects, one or more of theenumerated actions may be omitted or performed in a different order.

At action 505, the BS 105 may transmit a list of reference signals tothe UE 115. The list of reference signals may be transmitted as part ofan RRC message. The list of reference signals may also be communicatedover a series of messages, adding and/or removing reference signals fromthe list as determined by the BS 105. This list of reference signals maybe, for example, a list of possible PathlossReferenceRS from which somewill be used in transmission on the downlink for the UE 115 to measureand use for open loop power control (as one exemplary use).

At action 510, the BS 105 may send a configuration to the UE 115 for aCommon PathlossReferenceRS to use from those in the list received ataction 505. This may be a bit or combination of bits operating as anindex into the list of reference signals, or some other parameter thatthe UE 115 uses to select one of the reference signals from the list tobe used by a plurality of SDM uplink streams (e.g., the SDM uplinkstreams between a same BS 105 panel and a same UE 115 panel).

At action 515, the BS 105 may transmit a message or series of messagesdefining a group of uplink streams. In some aspects, the UE 115 may beconfigured with a structure which defines the CommonPathlossReferenceRS, and the group of uplink streams is within thatstructure. Alternatively, the UE 115 may be configured with a structurethat defines the group of SDM uplink streams, and the CommonPathlossReferenceRS is included within that structure. Accordingly, theorder of the configuration of the list of reference signals, indicationof the Common PathlossReferenceRS, and the configuration of the groupsof SDM uplink streams may occur in a variety of ways as discussed inthis disclosure.

In some aspects, the BS 105 may configure a group of streams in action515, without configuring a list of reference signals or indicating aPathlossReferenceRS as in actions 505 and 510. In that case, the UE 115may assume a default PathlossReferenceRS for the streams in the definedgroup. If the BS 105 configures neither a PathlossReferenceRS nor agroup of streams (as in action 515), the UE 115 may assume a respectivedefault PathlossReferenceRS for each individual stream.

At action 520, the BS may transmit the indicated reference signal, thecommon PathlossReferenceRS for example, to the UE 115. Other referencesignals may be transmitted by the BS either simultaneously or at othertimes, but the UE 115 is configured to utilize the CommonPathlossReferenceRS reference signal for each of the uplink beamsidentified at action 505 or action 510, such as for each referencesignal identified as part of the same group.

At action 525, the UE 115 may measure the transmitted reference signalthat was received at action 520. The UE 115 may use this measurement tomake a coarse determination of how to adjust the power of the SDM uplinkstreams for open loop power control.

At action 530, the UE 115 may adjust the uplink power of the SDM uplinkstreams sharing the common reference signal according to the measurementperformed at action 525. As this open loop power control captures commoncoarse changes due to UE 115 movement (or other environment change(s)),further variation/fine resolution control may occur via closed looppower control (which may be on a per-stream basis as opposed to thegrouped basis per panel between UE and BS with the open loop powercontrol according to embodiments of the present disclosure).

At action 535, the UE 115 may transmit uplink data to the BS 105. Thisuplink data is transmitted at a power as determined and implemented bythe UE 115 (such as by reference signal configuration module 408 of FIG.4 ) according to the reference signal measurement from action 525 andaction 530, respectively.

Actions 520-535 may repeat over a period of time without theconfiguration of the common reference signal changing. However, if theBS 105 determines to reconfigure the common reference signal, additionalactions may occur in FIG. 5 . Reasons for reconfiguration may includethe BS 105 (and/or TRP) that a UE 115 is communicating with changing, orwhen the UE 115 moves in relation to the BS/TRP for existing UL SDMstreams, or when the BS determines to change what is used as thereference signal (e.g., switching between using a synchronization signalblock (SSB) or a CSI-RS), or when there is a change in some channelcharacteristic (such as one of the beams being received at a much lowerpower than the rest of the beams in the group, as might occur when achange in the environment occurs that affects scattering of thestream(s)).

At action 540, the BS 105 may configure a different reference signal(e.g., Common PathlossReferenceRS) for the UE 115 to use in open looppower control. This reconfiguration of the common reference signal mayinclude adding or removing reference signals from the list of referencesignals (e.g., the list configured at action 505), in addition to achange in the indication of which of the reference signals in the listis to be used. The change in the Common PathlossReferenceRS may beperformed periodically, or only when determined to be necessary by theBS 105. Additionally, the UE 115 may indicate to the BS 105 a requestedCommon PathlossReferenceRS, which the BS 105 may or may not determine touse as requested.

Other exemplary actions may be taken in response to changes in theenvironment. For example, at action 545, the BS 105 may transmit amessage to the UE 115 to remove an uplink stream from the group. Thismay be done for a variety of reasons, e.g. one of the streams has achannel which has degraded to the point that it is no longer reliable.The removed uplink stream may be unused, or may be added to anothergroup either in the same message or through a separate message from theBS 105. Accordingly, action 545 may be optional.

At action 550, the BS 105 may add an uplink stream to the group. Thisuplink stream may be a newly established stream, or may be a stream thatwas previously assigned to a different group with a different CommonPathlossReferenceRS. This is another exemplary action that may occur dueto a change in the environment, and may be optional.

FIG. 6 is a flow diagram of a wireless communication method 600according to some aspects of the present disclosure. Aspects of themethod 600 can be executed by a computing device (e.g., a processor,processing circuit, and/or other suitable component) of a wirelesscommunication device or other suitable means for performing the steps.For example, a wireless communication device, such as the UEs 115 and/or400 may utilize one or more components, such as the processor 402, thememory 404, the reference signal configuration module 408, thetransceiver 410, the modem 412, and the one or more antennas 416, toexecute the steps of method 600. As illustrated, the method 600 includesa number of enumerated steps, but aspects of the method 600 may includeadditional steps before, after, and in between the enumerated steps. Insome aspects, one or more of the enumerated steps may be omitted orperformed in a different order.

At block 610, a UE 115 may receive, from a first BS, a messagecomprising a list of possible reference signals for a plurality of SDMuplink streams. This may be an RRC message, for example. As discussedabove with reference to FIG. 5 , such a message may be a singularmessage, or multiple messages which add and/or remove reference signalsfrom the list one at a time or more than one at a time.

At block 620, the UE 115 may receive, from the first BS, a message withconfiguration information indicating a first reference signal from amongthe list of reference signals (e.g., a Common PathlossReferenceRS). Insome aspects, the message may be a DCI message.

At block 630, the UE 115 may receive, from the first BS, a messageidentifying the plurality of SDM uplink streams as part of a firstgroup. The creation of the first group may be by a single message, or aseries of messages which may add and/or remove a stream to the group oneat a time or more than one at a time. The group is associated with aCommon PathlossReferenceRS which is to be used for each of the streamsin the group. In order to configure a new PathlossReferenceRS, the firstBS may send a single message indicating a new Common PathlossReferenceRSrather than a separate message for each individual stream in the group.In some aspects, the UE 115 may be configured with a structure whichdefines the Common PathlossReferenceRS, and the group of uplink streamsis within that structure. Alternatively, the UE 115 may be configuredwith a structure that defines the group of SDM uplink streams, and theCommon PathlossReferenceRS is included within that structure.Accordingly, the order of the configuration of the list of referencesignals, indication of the Common PathlossReferenceRS, and theconfiguration of the groups of SDM uplink streams may occur in a varietyof ways.

In some aspects, the first BS may configure a group of streams in action630 without configuring a list of reference signals or indicating aPathlossReferenceRS as in actions 610 and 620. In that case, the UE 115may assume a default PathlossReferenceRS for the streams in the definedgroup. If the first BS configures neither a PathlossReferenceRS nor agroup of streams (as in action 630), the UE 115 may assume a respectivedefault PathlossReferenceRS for each individual stream.

At block 640, the UE 115 may measure the currently indicated referencesignal from the first BS. This is done so that the UE can get a coarseestimate of changes in the paths of the SDM uplink streams associateswith the reference signal. While the individual beams will havevariations between them, the indicated reference signal is intended togive a close enough indication to be used for coarse power adjustmentsamong all the streams in the group.

At block 650, the UE 115 may apply a result from the measuring to eachstream among the plurality of SDM streams in the first group for openloop power control of the SDM uplink streams (e.g., those streamstransmitted from the same panel of the UE 115 to the same panel of thefirst BS).

At block 660, if there are any new SDM uplink streams that have beenestablished, then the UE 115 may receive, from a BS, a messagecomprising configuration information indicating a reference signal forthe additional SDM uplink streams. The BS may add the new SDM uplinkstreams to the existing first group of uplink streams, or to a separategroup. If added to the first group, then the new streams will share thesame Common PathlossReferenceRS. If added to a different group, then thenew streams will have a separate Common PathlossReferenceRS. Thisconfiguration includes established the group of uplink streams,configuring a list of potential reference signals, which may be the sameas the list of reference signals for the first group, and indicatingwhich of the reference signals is to be used for coarse poweradjustment. The BS in block 660 may be the same as the first BS, orcould be a different BS. When the BS is a different BS, this is similarto the scenario illustrated in FIG. 2 which shows beams from a UE 115 totwo different TRPs 205.

At block 670, the UE 115 may receive, from the first BS, a messagecomprising configuration information indicating a different referencesignal for the first group. The BS may determine at various times thatthe reference signal used for measuring the path and performing a poweradjustment on the uplink streams should change. It is not necessary,however, that this step be performed, as there may be no need for achange in the reference signal.

After block 670, the method 600 may repeat beginning at block 640,continuing to make reference signal measurements, and adjusting thepower of the uplink streams associated with the measured referencesignals.

Although not illustrated in FIG. 6 , the above aspects related to method600 may occur concurrently for multiple different panels between one ormore BS s and the UE 115. For example, as illustrated in FIG. 2 the UE115 may be connected to multiple TRPs at the same time, with multiplebeams between each TRP and the UE 115. Moreover, each TRP-UE connectionmay include multiple streams via the same panels at the respectivedevices, such that aspects of the present disclosure may apply. Thus,one or more of the blocks 610-670 may occur at the same time, atoverlapping times, and/or at different times for different groups ofstreams related to the different panel pairs between devices.

FIG. 7 is a flow diagram of a wireless communication method 700according to some aspects of the present disclosure. Aspects of themethod 700 can be executed by a computing device (e.g., a processor,processing circuit, and/or other suitable component) of a wirelesscommunication device or other suitable means for performing the steps.For example, a wireless communication device, such as the BSs 105 , theBS 300, and/or TRPs 205, may utilize one or more components, such as theprocessor 302, the memory 304, the reference signal configuration module308, the transceiver 310, the modem 312, and the one or more antennas316, to execute the steps of method 700. As illustrated, the method 700includes a number of enumerated steps, but aspects of the method 700 mayinclude additional steps before, after, and in between the enumeratedsteps. In some aspects, one or more of the enumerated steps may beomitted or performed in a different order.

At block 705, a BS 105 may transmit, to a UE 115, a message (e.g. an RRCmessage) configuring a list of potential reference signals. This may beperformed as a single message, or as a series of messages. For example,the BS 105 may transmit a separate message adding one reference signalto the list at a time, and may send messages removing reference signalsfrom the list as deemed appropriate by the BS 105. Further, the BS 105may configure a group of uplink streams that are configured for the samereference signal.

At block 710, the BS 105 may determine a reference signal for a commonreference for a plurality of SDM uplink streams. This may include, forexample, determining what reference signal (e.g., what commonPathlossReferenceRS) from among a list of reference signals possible forthe UE to use (e.g., as configured at block 705 above. Thisdetermination may be based on a number of factors. Generally, the SDMuplink streams may utilize beam paths that are similar enough such thata measurement of the common reference signal gives meaningfulinformation for all of them (for example, where the streams are viabeams from the same panel of each device communicating with the other).

At block 720, the BS 105 may transmit, to the UE 115, a message thatcontains the configuration information indicating the reference signalfor the plurality of SDM uplink streams as determined from block 715.This may be a single message, or a number of messages. For example, themessage may include messages forming a group of SDM streams, forming alist of potential reference signals, and a parameter selecting which ofthe reference signals to use for a pathloss reference. This transmissionmay be part of a DCI message to the UE 115, for example.

At block 730, the BS 105 may transmit the reference signal to the UE115. This transmission may occur on a regular basis, such that the UE115 may measure changes in the reference signal measurements over time.

At block 735, the BS 105 may receive, from the UE 115, a transmission(such as a PUSCH transmission) with a power level adjusted by ameasurement of the reference signal the BS 105 had transmitted to the UE115 at block 730.

At decision block 740, if the BS 105 determines that the UE 115 haschanged cells with which it is connected, then the method 700 proceedsto block 770 as discussed further below. Where the UE 115 is the entitythat makes the determination, decision block 740 would instead determineif a notification is received by the BS 105 from the UE 115 identifyingthat determination. If there is no change in cells, the method proceedsto decision block 750.

At decision block 750, if the BS 105 determines that a channelcharacteristic has changed, the method 700 proceeds to block 770. Wherethe UE 115 is the entity that makes the determination, decision block750 would instead determine if a notification is received by the BS 105from the UE 115 identifying that determination. Either way, the changein channel characteristic may be due to changes in reflection sources,scattering sources, atmospheric conditions, or a variety of otherfactors. If a characteristic has changed such that the currentlyindicated reference signal is no longer satisfactory, then the methodproceeds to block 770 as described below. Otherwise, the method proceedsto decision block 760.

At decision block 760, a determination may be made, by the BS 105, suchas on its own or as prompted by a request from the UE 115, that a newpreferred reference signal has been configured. For example, a BS 105may begin with a SSB reference signal used for the CommonPathlossReferenceRS, but may later configure a CSI-RS reference signalwhich is preferred (or vice-versa). If there is a new preferredreference signal, then the method proceeds to block 770 as describedbelow, otherwise it proceeds to block 730. The BS 105 may continue totransmit the reference signal, receive data from the UE 115 at adjustedpower levels, and monitor for conditions that would require a change inany of the configurations, including adding and removing referencesignals from the list, indicating a new PathlossReferenceRS as discussedbelow with reference to block 770, configuring new SDM uplink streams,or re-grouping the streams to name a few examples.

At block 770, the BS 105 may configure the UE 115 to use a differentreference signal (again, a common reference signal, such as a commonPathlossReferenceRS, for multiple streams sharing a panel betweendevices). This may be done in some aspects by simply changing theindicated Common PathlossReferenceRS using a single message, such as aDCI message identifying a different reference signal from a list. Inother examples, the change may include also changing which SDM uplinkstreams are grouped together, and/or which reference signals areincluded in the list of potential reference signals. Upon making thechange, the method 700 may proceed from block 770 back to theappropriate block, such as block 705 if the list of reference signals ischanged, or block 720 if changing just which reference signal isselected from the list, and proceed as further discussed above.

Further aspects of the present disclosure include the following:

-   -   1. A method of wireless communication comprising:

receiving, by a first wireless communications device from a secondwireless communications device, a message comprising configurationinformation indicating a reference signal for a plurality of spatialdomain multiplexing (SDM) uplink streams;

-   -   measuring, by the first wireless communications device, the        reference signal from the second wireless communications device;        and    -   applying, by the first wireless communications device, a result        from the measuring to each stream among the plurality of SDM        uplink streams.    -   2. The method of aspect 1, wherein the plurality of SDM uplink        streams are between a panel of the first wireless communications        device and a panel of the second wireless communications device.    -   3. The method of any of aspects 1-2, further comprising:    -   receiving, by the first wireless communications device from the        second wireless communications device, a first message        comprising a list of possible reference signals for the        plurality of SDM uplink streams, the message comprising a second        message and the configuration information comprising an        indication of the reference signal from among the list of        reference signals.    -   4. The method of any of aspects 1-2, wherein the message        comprises a first message, the method further comprising:    -   receiving, by the first wireless communications device from the        second wireless communications device, a second message        identifying the plurality of SDM uplink streams as part of a        first group.    -   5. The method of aspect 4, wherein the reference signal        comprises a first reference signal, the method further        comprising:    -   receiving, by the first wireless communications device from a        third wireless communications device, a third message comprising        configuration information indicating a second reference signal        for one or more additional SDM uplink streams, the first and        second reference signals being different and the one or more        additional SDM uplink streams are identified as part of a second        group.    -   6. The method of aspect 5, wherein the third wireless        communications device is different than the second wireless        communications device.    -   7. The method of any of aspects 1-6, wherein the applying        comprises:    -   performing a coarse power adjustment to the plurality of SDM        uplink streams.    -   8. A method of wireless communication comprising:    -   determining, by a first wireless communications device, a common        reference signal for a plurality of spatial domain multiplexing        (SDM) uplink streams;    -   transmitting, by the first wireless communications device to a        second wireless communications device, a message comprising        configuration information indicating the reference signal; and        transmitting, by the first wireless communications device to the        second wireless communications device, the reference signal.    -   9. The method of aspect 8, wherein the plurality of SDM uplink        streams are between a panel of the first wireless communications        device and a panel of the second wireless communications device.    -   10. The method of any of aspects 8-9, further comprising:    -   transmitting, by the first wireless communications device to the        second wireless communications device, a first message        comprising a list of possible reference signals for the        plurality of SDM uplink streams, the message comprising a second        message and the configuration information comprising an        indication of the reference signal from among the list of        reference signals.    -   11. The method of aspect any of aspects 8-9, wherein the message        comprises a first message, the method further comprising:    -   transmitting, by the first wireless communications device to the        second wireless communications device, a second message        identifying the plurality of SDM uplink streams as part of a        first group.    -   12. The method of any of aspects 8-9, wherein the message        comprises a first message, the method further comprising:    -   receiving, by the first wireless communications device from the        second wireless communications device, a second message        comprising configuration information indicating a different        reference signal for the plurality of SDM uplink streams.    -   13. The method of aspect 12, wherein the reference signal        comprises a synchronization signal block (SSB), and the        different reference signal comprises a channel state information        reference signal (CSI-RS), the method further comprising:    -   changing the reference signal used as the reference signal for        the plurality of SDM uplink streams to the different reference        signal.    -   14. The method of aspect 12, wherein the second message is sent        in response to a change in a characteristic of a channel        associated with one of the plurality of SDM uplink streams.    -   15. The method of any of aspects 8-14, wherein the applying        comprises:    -   performing a coarse power adjustment to the plurality of SDM        uplink streams.    -   16. A first wireless communications device comprising:    -   a transceiver configured to:        -   receive, from a second wireless communications device, a            message comprising configuration information indicating a            reference signal for a plurality of spatial domain            multiplexing (SDM) uplink streams;        -   measure the reference signal from the second wireless            communications device; and a processor configured to:        -   apply a result from the measuring to each stream among the            plurality of SDM uplink streams.    -   17. The first wireless communications device of aspect 16,        wherein the plurality of SDM uplink streams are between a panel        of the first wireless communications device and a panel of the        second wireless communications device.    -   18. The first wireless communications device of any of aspects        16-17, the transceiver further configured to:    -   receive, from the second wireless communications device, a first        message comprising a list of possible reference signals for the        plurality of SDM uplink streams, the message comprising a second        message and the configuration information comprising an        indication of the reference signal from among the list of        reference signals.    -   19. The first wireless communications device of any of aspects        16-17, wherein the message comprises a first message, the        transceiver further configured to:    -   receive, from the second wireless communications device, a        second message identifying the plurality of SDM uplink streams        as part of a first group.    -   20. The first wireless communications device of aspect 19,        wherein the reference signal comprises a first reference signal,        the transceiver further configured to:    -   receive, from a third wireless communications device, a third        message comprising configuration information indicating a second        reference signal for one or more additional SDM uplink streams,        the first and second reference signals being different and the        one or more additional SDM uplink streams are identified as part        of a second group.    -   21. The first wireless communications device of aspect 20,        wherein the third wireless communications device is different        than the second wireless communications device.    -   22. The first wireless communications device of any of aspects        16-21, wherein the applying comprises:    -   performing a coarse power adjustment to the plurality of SDM        uplink streams.    -   23. A first wireless communications device comprising:    -   a processor configured to:        -   determine a common reference signal for a plurality of            spatial domain multiplexing (SDM) uplink streams; and    -   a transceiver configured to:        -   transmit, to a second wireless communications device, a            message comprising configuration information indicating the            reference signal; and        -   transmit, to the second wireless communications device, the            reference signal.    -   24. The first wireless communications device of aspect 23,        wherein the plurality of SDM uplink streams are between a panel        of the first wireless communications device and a panel of the        second wireless communications device.    -   25. The first wireless communications device of any of aspects        23-24, the transceiver further configured to:    -   transmit, to the second wireless communications device, a first        message comprising a list of possible reference signals for the        plurality of SDM uplink streams, the message comprising a second        message and the configuration information comprising an        indication of the reference signal from among the list of        reference signals.    -   26. The first wireless communications device of any of aspects        23-24, wherein the message comprises a first message, the        transceiver further configured to:    -   transmit, to the second wireless communications device, a second        message identifying the plurality of SDM uplink streams as part        of a first group.    -   27. The first wireless communications device of any of aspects        23-24, wherein the message comprises a first message, the        transceiver further configured to:    -   receive, from the second wireless communications device, a        second message comprising configuration information indicating a        different reference signal for the plurality of SDM uplink        streams.    -   28. The first wireless communications device of aspect 27,        wherein the reference signal comprises a synchronization signal        block (SSB), and the different reference signal comprises a        channel state information reference signal (CSI-RS), the        processor further configured to:    -   change the reference signal used as the reference signal for the        plurality of SDM uplink streams to the different reference        signal.    -   29. The first wireless communications device of aspect 27,        wherein the second message is sent in response to a change in a        characteristic of a channel associated with one of the plurality        of SDM uplink streams.    -   30. The first wireless communications device of any of aspects        23-29, wherein the applying comprises:    -   performing a coarse power adjustment to the plurality of SDM        uplink streams.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of [at least one of A, B, or C]means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

As those of some skill in this art will by now appreciate and dependingon the particular application at hand, many modifications, substitutionsand variations can be made in and to the materials, apparatus,configurations and methods of use of the devices of the presentdisclosure without departing from the spirit and scope thereof. In lightof this, the scope of the present disclosure should not be limited tothat of the particular aspects illustrated and described herein, as theyare merely by way of some examples thereof, but rather, should be fullycommensurate with that of the claims appended hereafter and theirfunctional equivalents.

What is claimed is:
 1. A method of wireless communication comprising:determining, by a first wireless communications device, a commonreference signal for a plurality of spatial domain multiplexing (SDM)uplink streams; transmitting, by the first wireless communicationsdevice to a second wireless communications device, a message comprisingconfiguration information indicating the reference signal; andtransmitting, by the first wireless communications device to the secondwireless communications device, the reference signal.
 2. The method ofclaim 1, wherein the plurality of SDM uplink streams are between a panelof the first wireless communications device and a panel of the secondwireless communications device.
 3. The method of claim 1, furthercomprising: transmitting, by the first wireless communications device tothe second wireless communications device, a first message comprising alist of possible reference signals for the plurality of SDM uplinkstreams, the message comprising a second message and the configurationinformation comprising an indication of the reference signal from amongthe list of reference signals.
 4. The method of claim 1, wherein themessage comprises a first message, the method further comprising:transmitting, by the first wireless communications device to the secondwireless communications device, a second message identifying theplurality of SDM uplink streams as part of a first group.
 5. The methodof claim 1, wherein the message comprises a first message, the methodfurther comprising: receiving, by the first wireless communicationsdevice from the second wireless communications device, a second messagecomprising configuration information indicating a different referencesignal for the plurality of SDM uplink streams.
 6. The method of claim5, wherein the reference signal comprises a synchronization signal block(SSB), and the different reference signal comprises a channel stateinformation reference signal (CSI-RS), the method further comprising:changing the reference signal used as the reference signal for theplurality of SDM uplink streams to the different reference signal. 7.The method of claim 5, wherein the second message is sent in response toa change in a characteristic of a channel associated with one of theplurality of SDM uplink streams.
 8. The method of claim 1, wherein theapplying comprises: performing a coarse power adjustment to theplurality of SDM uplink streams.
 9. A first wireless communicationsdevice comprising: a processor configured to determine a commonreference signal for a plurality of spatial domain multiplexing (SDM)uplink streams; and a transceiver configured to: transmit, to a secondwireless communications device, a message comprising configurationinformation indicating the reference signal; and transmit, to the secondwireless communications device, the reference signal.
 10. The firstwireless communications device of claim 9, wherein the plurality of SDMuplink streams are between a panel of the first wireless communicationsdevice and a panel of the second wireless communications device.
 11. Thefirst wireless communications device of claim 9, the transceiver furtherconfigured to: transmit, to the second wireless communications device, afirst message comprising a list of possible reference signals for theplurality of SDM uplink streams, the message comprising a second messageand the configuration information comprising an indication of thereference signal from among the list of reference signals.
 12. The firstwireless communications device of claim 9, wherein the message comprisesa first message, the transceiver further configured to: transmit, to thesecond wireless communications device, a second message identifying theplurality of SDM uplink streams as part of a first group.
 13. The firstwireless communications device of claim 9, wherein the message comprisesa first message, the transceiver further configured to: receive, fromthe second wireless communications device, a second message comprisingconfiguration information indicating a different reference signal forthe plurality of SDM uplink streams.
 14. The first wirelesscommunications device of claim 13, wherein the reference signalcomprises a synchronization signal block (SSB), and the differentreference signal comprises a channel state information reference signal(CSI-RS), the processor further configured to: change the referencesignal used as the reference signal for the plurality of SDM uplinkstreams to the different reference signal.
 15. The first wirelesscommunications device of claim 13, wherein the second message is sent inresponse to a change in a characteristic of a channel associated withone of the plurality of SDM uplink streams.
 16. The first wirelesscommunications device of claim 9, wherein the applying comprises:performing a coarse power adjustment to the plurality of SDM uplinkstreams.
 17. An apparatus for use in a first wireless communicationsdevice, the apparatus comprising: means for determining a commonreference signal for a plurality of spatial domain multiplexing (SDM)uplink streams; means for initiating transmission, to a second wirelesscommunications device, a message comprising configuration informationindicating the reference signal; and means for initiating transmission,to the second wireless communications device, the reference signal. 18.The apparatus of claim 17, wherein the plurality of SDM uplink streamsare between a panel of the first wireless communications device and apanel of the second wireless communications device.
 19. The apparatus ofclaim 17, further comprising: means for initiating transmission, to thesecond wireless communications device, a first message comprising a listof possible reference signals for the plurality of SDM uplink streams,the message comprising a second message and the configurationinformation comprising an indication of the reference signal from amongthe list of reference signals.
 20. The apparatus of claim 17, whereinthe message comprises a first message, and the apparatus furthercomprises: means for initiating transmission, to the second wirelesscommunications device, a second message identifying the plurality of SDMuplink streams as part of a first group.